*{
    margin: 0;
    padding: 0;
}
ul,li{
    list-style: none;
}
.fl{
    float: left;
}
.fr{
    float: right;
}
.clearfix::after{
    display: block;
    clear: both;
    content: '';
}
.main{
    /* width: 640px; */
    margin: 0 auto;
}